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Imaging to the Rescue in Fight Against Invasive Bugs

Photonics.comAug 2015
GREENBELT, Md., Aug. 27, 2015 — Ravenous insects smaller than a penny continue to migrate from the Southeast, threatening to destroy millions of pine and ash trees in the Northeast. Now NASA has teamed with the U.S. Forest Service to combat the problem using an array of optical imaging techniques.

Scientists at NASA’s Goddard Space Flight Center are using an airborne instrument first developed in 2011 called G-LiHT — for Goddard lidar hyperspectral and thermal imager — to aid the Forest Service in understanding and combatting two types of insects in particular: the southern pine beetle and the emerald ash borer.

The southern pine beetle infests about 1000 acres of land in New York and is now moving into Connecticut and Massachusetts. The emerald ash borer, meanwhile, is responsible for killing tens of millions of trees in the Northeast already and has set up camp in 24 other states and parts of Canada.

The G-LiHT device sits inside an airplane's cockpit, over an open camera port that allows it to look down from 1000 feet up at a speed of about 150 mph. Courtesy of NASA/Goddard Space Flight Center.

"We're probably looking at the eradication of most of the ash trees in the United States and Canada," said Goddard Earth scientist Bruce Cook, noting that insects like the emerald ash borer will continue their feast for the foreseeable future.

The G-LiHT device, mounted to a Forest Service airplane, could help. Cook and fellow scientists from both agencies have been observing forests in Massachusetts, New Hampshire, New York and Rhode Island this summer.

G-LiHT shines a laser on the forest canopy and ground surface to measure signs of forest health. It monitors insect damage and maps specific areas at risk, creating detailed 3D images of individual trees, from the trunk to the leaves.

With an imaging spectrometer, G-LiHT is also able to see reflected sunlight that is invisible to the naked eye. This helps scientists gather useful information about the trees, such as changes in leaf pigments that plants use for photosynthesis; declining photosynthesis indicates sick trees, Cook said.

G-LiHT also features a thermal camera that allows identification of infested trees, which appear warmer when insects girdle their trunks and interrupt the natural flow and transpiration of water.

The device's different sensors operate almost like the different human senses, Cook said. "One sense cannot totally inform you. A more complete picture of forest composition and health can be obtained with multisensor instrument packages."

Observation at ground level is necessary, too, to examine the health of individual trees; this allows the scientists to better interpret the information gathered via G-LiHT.

Both the southern pine beetle and emerald ash borer pose "astronomical damages for the forestry industry in costs for post-infestation control, cleanup and replanting," according to Ryan Hanavan, an entomologist with the Forest Service.

"We're literally talking about millions to even billions of dollars in impact to the forestry industry," Cook said, adding that infestation prevention "could save millions of dollars to municipalities and landowners, who could be responsible for disposing of dead trees."

Not only are the pests detrimental to the economy, they also jeopardize Mother Earth's overall health. Unhealthy forests contribute to biodiversity loss, while healthy ones help offset increasing levels of atmospheric carbon dioxide, a known contributor to climate change.

An acronym of light detection and ranging, describing systems that use a light beam in place of conventional microwave beams for atmospheric monitoring, tracking and detection functions. Ladar, an acronym of laser detection and ranging, uses laser light for detection of speed, altitude, direction and range; it is often called laser radar.